Stack-draft control



Aug. 27, 1929. c. H. QUINN 8 1,725,888

STACK DRAFT CONTROL Filed July 25, 1924 Patented Aug. 27, 1929.

UNITED STATES PATENT OFFICE.

CHARLES H. QUINN, OF SAN IEIM-KNCISCO, CALIFORNIA.

STACK-DRAFT CONTROL.

Application filed July 25,

mined movements of a master lever or other controlling motive power apparatus used to move dampers between a boiler and the smoke stack breeching.

It is well known that the ordinary damper consists generally of a plate suitably pivoted and having means whereby it may be swung to a greater or less extent, as desired, for varying the size of the opening and conseucntly regulating the draft. Whenever the damper is moved the projected opening be tween the damper edge and the wall of the breeching will continually change. Likewise, the character of the opening as defined by the walls of the breeching and the edge of the damper continually changes. Slightly varying smoke stack pressure for the same opening of this kind will give wide variations in the flow of gas through the opening of the same area.

It is with the above facts in view that I have designed the present invention which has for a more particular objectthe provision of a novel damper means for maintaining, within certain limits, constant draft pressure in the rear end of boiler gas exits, the means including a series of independently operable damper elements of different sizes which may, if found preferable, have individual or separate uptakes.

To the attainment of the foregoing and other objects and advantages, the invention consists in the details of construction and arrangement of parts to be hereinafter more fully described and claimed, and illustrated in the accompanying drawings, it being, however, understood that various changes and modifications may be made to increase the utility and widen the field of adaptability of the device, provided such variations constitute no departure from the spirit of the invention or the scope of the claims hereunto appended.

In the drawings wherein like. reference characters designate corresponding parts throughout the several views:

Figure 1 is a side elevation of a stack breeching associated with a furnace, the

1924. Serial No. 728,238.

latter being represented diagrammatically and in section, the figure showing my damper arrangement applied.

Figure 2 is a vertical section through the breeching showing the dampers in place and in closed position.

Figure 3 is a cross section on the line 3-3 arrows, and showing a plan of the dampers.

Referring more particularly to the drawings, the numeral 1 designates a furnace from which leads an outlet 2 communicating with the stack breeching 3. These elements are represented only generally and not in detail as they constitute no part of the invention, the illustration being for the purpose of indicating the location of the draft control mechanism.

In the actual carrying out of the invention I provide a plurality or series of damper elements or plates 4 arranged in parallel as shown and pivoted in some suitable manner, as for instance by trunnions 5 and 6 which are here represented as located centrally of the ends of the plates, though it is obvious that the pivoting might be accom plished in some other manner and at some other points if found advisable for any reason. The trunnions 6 are illustrated as formed with cranks 7 with which are pivotally connected links or rods 8 which extend to any desired operating means,'either manually or power controlled.

In the present case the dampers 4 are all represented as being of different widths and it is preferable, though not essential, that each be located within its own separate uptake or fine, indicated at 9, theseuptakes varying in height and the longest being preferably associated with the smallest damper, though such is not necessarily the case.

Whereas the ordinary type of damper is opened to a variable extent to obtain the desired draft, the intention in the present instance is that one or more of the damper elements be opened entirely to obtain a cer tain fixed draft. To increase the draft, additional dampers may be opened or a larger one may be opened in place of a previously opened small one, there being no restriction desired as to the exact manner of manipulation.

From the work imposed. on dampe as of Figure 2, looking in the direction of the draft pressure regulators in boiler operation, it is obvious that with a constant stack draft that between a minimum opening of definite dimensions and another opening having larger dimensions, the proportion of gases passed through the first and second is not in proportion to the area of the two orifices under consideration. It is this fact which renders the ordinary type of pivoted single plate damper inefficient as the adjustment is too critical to obtain the exact-desired re sults. The damper mechanism constructed in accordance with my invention is free from all such defects as are present in the prior devices, especially as there is no necessity for partially opening any of the damper elements, the opening movement in every instance being definite and fixed and the operation being accomplished by entirely opening either a larger number of damper elements or a larger damper. As any number of dampers may be installed, the increment of increase or decrease in damper opening may be anything desired. As previously noted, the stack draft will vary as the opening through the damper mechanism is increased or decreased and it is to offset this variation that the Width of the dampers may be varied from any minimum to any maximum desired. It is to further assist in reducing this variation to a minimum that each damper is preferably provided With its individual uptake and in actual practice the height of the uptake may be made anything between a flat opening up to any height of auxiliary flue or passage that the outlet connection to the breeching will permit.

While any preferred master control mechanism may be employed for operating the damper elements, attention is called to the fact that this particular apparatus is well adapted for use in connection with pulverized fuel feeding mechanism.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. A furnace stack having substantially its entire cross sectional area divided into separate passages, and a damper within each passage whereby the draft through the stack may be varied while maintaining one or more of the individual dampers either in entirely closed or entire open position.

2. A furnace stack having substantially its entire cross sectional area divided into separate passages of different sizes, and a damper movably mounted within each passage whereby the draft may be accurately regulated by opening an individual damper and leaving the remaining ones entirely closed.

8. A furnace stack having substantially its entire cross sectional area divided into a plurality of passages of progressively differing sizes, and a separately operable damper within each passage whereby the draft may be accurately regulated by opening one or more dampers of selected sizes without disturbing the others.

4. A furnace stack having substantially its entire cross sectional area divided into separate passages of different lengths, and a damper movably mounted within each passage whereby the draft may be accurately regulated by opening an individual damper and leaving the remaining ones entirely closed.

5. A furnace stack having substantially its entire cross sectional area divided into separate passages of different cross sectional sizes and'lengths, and a damper movably mounted Within each passage whereby the draft may'be accurately regulated by opening one or more dampers of selected sizes without disturbing the others, the passages having a length inversely proportional to the cross sectional area.

In testimony whereof I afiix my signature.

CHARLES H. QUINN. 

